2. We have five
main sense
The eyes organs.
The tongue
The ears
The nose
The skin
3. All senses depend on the
nervous system.
Our sense organs start to work
when something stimulates
special nerve cells called
receptors.
The receptors send nerve
impulses along the sensory
nerves to the brain.
Your brain then tells you what
the stimulus is.
4. The light rays enter the eye through
the cornea, which is a thick,
transparent protective layer on the
surface of your eye. Then the light
rays pass through the pupil (the dark
circle in the centre of your eye) and into
the lens.
cornea
pupil
iris
lens
When light rays pass through your pupil, the muscle called the
iris (coloured ring) changes the size of the pupil depending on
the amount of light that's available. If there is too much light,
your pupil will shrink but if there is very little light available, the
pupil will enlarge.
5. The lens focuses the image onto the back surface of the
eyeball, called the retina.
The retina, which is the size of your thumbnail, is filled with
approximately 150 million light-sensitive cells that send the
information to the brain by the optic nerve.
6. The nose is the organ for smell.
The nose has two holes called nostrils .
The nostrils and the nasal passages are separated by a
wall called septum.
Closer to the tip of the nose, the septum is made of cartilage,
which is flexible.
7. Behind the nose, in the
middle of the face, is a space
called nasal cavity. It
connects with the throat.
When we breathe, the air
goes through the nasal
cavity, down the throat, into
your trachea (windpipe)
and your lungs.
8. Scents or smells also
travel with the air.
At the top of the nasal
cavity there are some
sensitive cells in the
olfactory bulb that send
signals along the olfactory
nerve to the brain, which
tell us what we smell.
olfactory bulb
olfactory nerve
nasal cavity
olfactory bulb
bone
mucus sensitive cells
9. Your tongue and the roof of your mouth are covered with tiny taste
buds. We have almost 10,000 taste buds inside our mouths.
When you eat something the
receptor cells, located in
your tastes buds, send
messages through sensory
nerves to your brain. Your
brain then tells you what
flavours you are tasting.
10. Your taste buds can recognize
four basic kinds of tastes:
sweet, salty, sour, and bitter.
The salty/sweet taste buds are
located near the front of your
tongue
The sour taste buds line the
sides of your tongue
The bitter taste buds are
found at the very back of your
tongue.
11. Choose a number for:
•Sour
•Salty
•Bitter
•Sweet
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12. The ear is an organ for hearing and balance.
It consists of three parts: the outer ear, the
middle ear, and the inner ear.
13. www.audigygroup.com
When an object makes a noise, it
sends vibrations or sound waves
through the air. These vibrations are
collected by the outer ear and send
into the ear canal.
14. As the vibrations move into the
middle ear, they hit the eardrum
and makes it vibrate as well.
That vibration passes to the three
little bones called hammer, anvil
and stirrup.
Finally the vibration is transferred
to the cochlea into the inner ear,
and from the cochlea to the brain
through the auditory nerve. * The stirrup is the smallest bone in
* The stirrup is the smallest bone in
the human body (it is 0.25 to 0.33
cm long).
the human body (it is 0.25 to 0.33
cm long).
15. Your sense of touch is found all
over the body. This is because
your sense of touch originates in
the bottom layer of your skin
called the dermis.
The dermis is filled with many
tiny nerve endings which give
you information about the things
your body comes in contact.
16. The nerve endings carry the information to the
spinal cord, which sends messages to the
brain.
The nerve endings in your skin can tell you if
something is hot or cold. They can also feel if
something is hurting you.
